ML18064A672

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Requests That NRC Approve Code Case N-474-2 for Use of Alloy 690 Matl
ML18064A672
Person / Time
Site: Palisades Entergy icon.png
Issue date: 03/29/1995
From: Haas K
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9504060045
Download: ML18064A672 (5)
v • d • e


Text

consumers Power KurtM. Haas Plant Safety and Licensing Director POWERING MICHIGAN'S PllOGRESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 March 29, 1995 Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT REQUEST FOR APPROVAL OF CODE CASE N-474-2 FOR USE OF ALLOY 690 MATERIAL Palisades is planning to complete a number of NDE inspections during the 1995 refueling outage designed to identify any Primary Water Stress Corrosion Cracking (PWSCC) in Alloy 600 safe ends and nozzles in the Primary Coolant System (PCS). The extent of these inspections is described in our Alloy 600 Project plan which was submitted to the NRC on February 27, 1995. As part of our planning effort, we have procured some spare safe ends, nozzles, and bulk material from which larger nozzles or safe ends could be fabricated. The material we plan on using for these repairs and replacements is Alloy 690 (N06690), which has been proven to be less susceptible to PWSCC than the original Alloy 600 material. The smaller nozzles and safe ends we require were procured to material specifications approved by ASME Code Case N-474-1 and endorsed by the NRC in accordance with Regulatory Guide 1.85, "Material Code Case Acceptability ASME,Section III, Division 111

In accordance with footnote 6 of 10 CFR 50.55a, we request ~pproval for use of Code Case N-474-2 for Class 1 components within the Palisades Primary Coolant System. NRC approval for use is requested prior to beginning the 1995 refueling outage, which is scheduled to start in late May of this year. We acknowledge that use of the forged (SB-564) Alloy 690 components is a contingency action that may not be required. Prior NRC approval of this contingency is important, however, to support sound outage planning and preclude the economic penalties associated with potential outage delays.

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  • 2 Pursuant to 10 CFR 50.55a(a)(3) and the justification provided in Attachment 1, we believe that Code Case N-474-2 provides an acceptable *lternative to the current ~RC requirements.

SUMMARY

OF COMMITMENTS This letter contains no new commitments.

I~

Kurt MHaas Plant Safety and Licensing Director CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades Attachment

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i.. -- r' ATTACHMENT I Consumers Power Company Palisades Plant Docket 50-255 JUSTIFICATION FOR USE OF ALLY 690 MATERIAL IN ACCORDANCE WITH CODE CASE N-474-2 2 Pages

JUSTIFICATION FOR USE OF ALLY 690 MATERIAL IN ACCORDANCE WITH CODE CASE N-474-2 Code Class: 1

Subject:

Acceptability Of Forged N06690 Material Certified To SB-564 For Use As A Class 1 Pressure Boundary Such As For Repair Or Replacement Of N06600 Items Within The Palisades Plant Primary Coolant System.

Component Number: The intended use of the N06690 material would primarily be as replacement of Alloy 600 (N06600) material in the PCS.

CODE SPECIFICATIONS ASME Code Case N-474-1 "Design Stress Intensities and Yield Stress Values for UNS N06690 With Minimum Specified Yield Strength of 35 ksi, Class 1, ComponentsSection III, Division 1 allows the use of N06690 material 11 certified to ASME SB-163 "Specification For Seamless Nickel and Nickel Alloy Condenser and Heat Exchanger Tubes," SB-166 "Specification for Nickel-Chromium-Iron Alloy (UNS N06600 and N06690) Rod, Bar, and Wire," SB-167 "Specification For Nickel-Chromium-Iron Alloy (UNS N06600 and N06690) Seamless Pipe and Tube," and SB-168 "Specification For Nickel-Chromium-Iron Alloys (UNS N06600 and N06690) Plate, Sheet, and Strip" in Class 1,Section III construction. This Code Case was approved by ASME on March 5, 1990 and endorsed for use by the NRC under Regulatory Guide 1.85 "Material Code Acceptability ASME,Section III, Division 1 11 Revision 2 to the ASME Code Case N-474-2 "Design Stress Intensities and Yield Strength Values for UNS N06690 With a Minimum Specified Yield Strength of 35 ksi, Class 1 Components,Section III, Division 1 was approved by ASME on 11 December 9, 1993, and expands the Code Case by including the use of forged N06690 material certified to SB-564 "Specification For Nickel Alloy Forging" for use in Class 1,Section III construction.

BASIS FOR JUSTIFICATION Inspections at Palisades have determined that Primary Water Stress Corrosion Cracking (PWSCC), whi~h is a potential failure mechanism of N06600 components, has degraded one power operated relief valve safe end and two pressurizer temperature element nozzles made of N06600 material. Consumers Power Company (CPCo) is currently developing contingency plans in the event that PWSCC cracking is detected in other N06600 nozzles or safe ends during future inspections. These contingency plans include the procurement of N06690 material for possible use in repair or replacement of N06600 items. N06690 is known for its excellent corrosion resistance in various environments, including typical PWR environments. It has been shown to be less susceptible to PWSCC than N06600. Consumers Power Company is in the process of purchasing N06690 forgings so that potential critical path time during the inspection outage can be minimized in the event that repair or replacements of large nozzles or safe ends are necessary.

  • 2 N06690, a nickel-chromium-iron alloy, has already been accepted by the U.S.

NRC per Code Case N-474-1 for use in Class 1 construction. Code Case N-474-1 approved the use of the N06690 material for condenser and heat exchanger tubing; rod, bar, wire, plate, sheet or strip; and as seamless pipe and tube.

However, N06690 produced as a forging (SB-564) was not addressed by Code Case N-474-1. Code Case N-474-2 has since been issued and includes N06690 material produced as a forging to SB-564. Since forged N06690 material retains essentially the same corrosion resistance and mechanical properties as N06690 produced in other shapes under Code Case N-474-1, it should be equally acceptable for use in a primary coolant system environment.

Pursuant to 10 CFR 50.55a(a)(3), it is requested that Code Case N-474-2 be endorsed for use at Palisades on the basis that forged N06690 material (SB-564) meeting the requirements of the Code Case is an acceptable material to be used in construction of Class 1 components conforming to the requirements of Section III, Division 1. Revision 2 of the Code Case requires that the material produced as a forging meet the same requirements as N06690 material produced as tube, rod, bar, wire seamless pipe, plate, sheet and strip, such that the material as a forging will be acceptable for Class 1 construction.

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